The present invention relates to a reaming device, and in particular to a reaming device providing a reliable connection between a carbon fiber composite shaft and an interface element molded thereon.
Intramedullary nailing is the method of choice for the fixation of fractures in long bones, in particular bones in long extremities. To have full access to the intramedullary channel, a shaft of a reamer has to be flexible enough in a bending direction to bypass soft tissue and conform to bone curvature. The shaft also has to be rigid enough to convey torsion to the reamer head. Prior art reaming devices have a shaft design consisting of a helix in which residues can be trapped during the reaming procedure, so that the cleaning of the reaming device in hospitals prior to the next usage is complicated, in particular in a sterilization process. The adequate cleaning of the instrument in hospitals demands a great effort and takes a lot of time. Further, some hospitals are not prepared to clean such critical devices because of the great effort involved.
In some prior art reaming devices, a helix shaft is replaced by a shaft made of so called nitinol, which is a material having a high degree of elasticity (super elasticity) to provide enough flexibility. Nitinol is an acronym for NIckel TItanium Naval Ordnance Laboratory. Nitinol is the inter-metallic phase NiTi having a regular cubic crystal structure being different of the structure of titanium or nickel. Nitinol comprises about 55% nickel and about 45% titanium. Owing to the fact that the nitinol shaft is made of a single tube, the cleaning effort in the hospital is less exhausting. However, recent investigations have shown that the nitinol material has a catastrophic failure mode. In particular, some reports have pointed out that some breakages in multiple fragments of the nitinol shaft occurred during the reaming process during the intervention process in hospitals. Further, the nitinol material is a very expensive material.
EP 253526 and U.S. Pat. No. 4,751,922 relates to a shaft made of a composite material of filamentous fibers and an appropriate resin.
From US 2007/0015107, a root canal instrument having an abrasive coating and method for the production thereof is known, wherein the described root canal instrument has a core of a flexible elastic material having a shape memory, wherein the core furthermore has a coating with abrasive particles, wherein the core is made from a nickel-titanium alloy or from a plastic material, e.g. carbon fibre reinforced plastics material.
CH 668690 relates to a probe electrode cable for medical purposes, e.g. electro cardiogram test, using carbon fibre impregnated plastic insulating coating as a cover with a lead coupled to the test equipment.
US Patent Publication No. 2010/0239380 relates to a reaming device with a carbon fiber shaft , an interface element and a connecting agent. The disclosure of 2010/0239380 is incorporated herein by reference.